Carcinoma of the prostate is the most common cancer among males in the United States. It is estimated that there will be 122,000 newly diagnosed cases and 32,000 deaths resulting from the disease in 1991. The majority of patients who manifest clinical evidence of the disease present with locally advanced or metastatic disease. The high prevalence of prostate cancer in the general population is also reflected by the presence of treatment for suspected benign disease. Prostate cancer is found in 30% of men over 50 years old in autopsy studies and this rate triples by the 9th decade. This suggests that prostate cancer may have a period of latency and may be present for a long time prior to its clinical manifestations. The prevalence of prostate cancer shows remarkable geographic and racial differences. It is relatively rare in oriental males compared to whites in the United States. American black male on the other hand have the highest incidence of this cancer among any ethnic or racial group. This trend is present at every age and socioeconomic level. The causes of this peculiar racial difference are not clear, neither are the reasons why prostate cancer in Black Americans tends to be histologically less differentiated, has a more aggressive growth pattern, and is associated with mortality rates that are 50% higher than those encountered in white males in the United States. It may be postulated that there is a higher prevalence of prostate cancer in Black Americans and therefore the incidence of advanced cancer in proportionately greater, that Black Americans are less likely to access the health care system than their white counterparts and therefore present with more advanced disease, or that the biology of prostate cancer in different, more aggressive in the black population. In order to define the age and race related prevalence of prostate cancer in the general population, to study occult and premalignant lesions, and to compare biological features of prostate cancer between black and white individuals, we initiated a detailed study of the prostates of men deceased of traumatic causes and autopsied by the Medical Examiner of Wayne County, Michigan, a large urban area. In order to identify the earlier premalignant or malignant changes, all men older that 20 years of age are to be included in the study. The prostate glands are removed en-block, serially sectioned at 3-5 mm intervals and histologically evaluated for presence of intraepithelial neoplasia and prostate cancer. Specimens with cancer of premalignant changes are studied further by image analysis to determine their DNA content. The results of this study will demonstrate the age and race related prevalence of premalignant and malignant prostatic changes in large urban population, suggest similarities or differences in indicators of biological activity, and provide essential information for the rational design of future diagnostic and treatment strategies.